Health

How Long Will the Pandemic Last? Rate of Growth of Active Cases Holds Key.

Based on the current trend line of active cases, the growth may be slowing but India will hit its peak only when daily recoveries outpace new cases. There are signs this may be happening in Delhi, which is why other metros need to pay attention to its strategy.

Just over a  week ago, Prime Minister Modi asked his ministers to prepare “emergency plans” to deal with the spike in COVID cases in the five most severely affected states of the country. If one is looking for an admission from the government that its lockdown had failed, then this is it: instead of taking 21 days, Modi’s Mahabharata has lasted over 100 days. And the battle is only growing more intense by the day.

So how long will it last? How long before the case count reaches its peak and starts to decline? After how many deaths? If anyone in the government has an idea, she or he has kept it a deep secret. Mercifully, we have enough data now to make a reasonable estimate by ourselves. The news is not all that good, but the data on the rate of growth of active cases (i.e. total cases minus those who have recovered)  is sufficiently reassuring to make panic unnecessary. While across India, daily new cases are outpacing daily recoveries, the picture in Delhi is somewhat reassuring and could serve as a guide for what needs to be done if the duration of the pandemic is to be shortened.

The following table gives data, from  May 15 till July 6, for the total number of cases, the number of patients who have recovered, and the number of patients under active care.

May 15 has been chosen as the starting date because phase 3 of the lockdown had ended and normal life was just being resumed. It therefore gave the data a fairly uniform base, free of policy change-induced shocks. A comparison of the rates of change in these parameters makes it possible to discern the slowing down of the diseases and, barring, a surge in news cases, broadly map the trajectory of cases.

Of course, a caveat is needed. Two big confounding factors remain testing rates and the government’s denial of community transmission. Recovery rates do increase because that’s the natural course during a pandemic and we won’t discover more new cases unless we test more, which is why leading epidemiologists like Dr Jayaprakash Muliyil think most cases are going under the radar. For this exercise, however, we will take the government’s data at face value.

What the graph tells us

Column 1 shows that although the absolute number of new cases has kept increasing,  the rate of  growth has  slowed from doubling in 14 days till May 29, to 17 days by June 14. It has taken 20 days to double again by July 3-4. This slowdown is welcome, but it is the least reliable (although most quoted) datum for charting the future course of the disease, because it is the one most affected by government interventions.

In India, this is particularly so because a good part of the increase is a product of more intensive – though by no means adequate or even geographically uniform – testing, which has gone up from around 4200 tests per day on March 24, to more than 150,000 today. One consequence of this is the inclusion of a higher proportion of those who are mildly affected by the disease.

Column 2 gives a sense of the number of patients who recover every day. This has been rising much more rapidly than the infection rate throughout the 46 days of the survey, but the rate of recovery too has been slowing down. Recoveries per day doubled in just 9 days by May 24, then doubled again in another 12 days by June 5. This slowed down further after the lockdown was lifted to doubling in 15.5 days ( June20/21). In the last days of June the rate of recovery has slowed down still more, with the doubling rate likely to be 17 days.

Column 3 shows that the higher recovery rate has been mirrored by a slower growth of active cases. Whereas new cases increased by 6.5 times between May 15 and  June 30, active cases increased by only four times. Better still, the doubling rate of active cases has also slowed sharply from 18 days  between May 15 and June 3, to 25 days from June 2 to  June 30.

Columns 4 and 5, plotted in the graph above, give us a sense of the  average rate of improvement in these two parameters per day. It is 0.63% per day in recoveries and 0.54% per day in active cases. A simple linear extrapolation would then suggest the tide turning in September.

While comforting, however, this does not tell the whole story, for all-India, there are more new patients detected with COVID-19 every day than there are patients who have recovered:

The challenge for India is to narrow the gap between the blue and green curves so that eventually daily recoveries outpace daily new infections. That point would mark the peak, though hitting the peak, by itself is no guarantee of the pandemic’s end.  In Europe, China, Malaysia  and several others in Asia, the active disease count fell fairly rapidly after that point as recoveries continue to grow. But then there are also countries which have either plateaued after peaking, or had a resurgence of cases (eg. Iran) thereafter. It is too early to tell which way India will go.

In India, there are three big imponderables. First, the danger of the community transmission we see in large metros spreading to rural areas and smaller cities and  towns. Second, the inadequate amount of testing, particularly in some populous states like Uttar Pradesh and Bihar, gives us an inexact sense of the total disease count. But by far the most disruptive of developments that could derail these predictions is the inability of even the augmented treatment facilities we are putting in place to cope with the sheer number of active cases there will be. By the beginning of September, at the present 25-day doubling rate, active cases will rise to around 1.2 million patients by that date.

Where will so many beds come from? In  2015, Price Waterhouse had estimated that there were 1.3 beds per 1000 population, in India. This amounted to 1.75 million beds, which  was far from sufficient to meet the requirements that arose out of  accidents, diseases, localised epidemics, pregnancies and premature births. Even if  the number of beds has  gone up 50 percent since then, and that all of the increase can be sequestered  for coping with the pandemic, There will still be a shortage of 600,000 beds. The inevitable decline in the quality of treatment that will result from trying to cope, will slow down recovery and increase the number of deaths further.

As the enormity of the problem dawns upon the state governments, the knee-jerk reaction of many of them could be to reimpose lockdowns, or  harden them where they already exist. This must not happen.

Our bitter experience of the past three months has shown that any  lockdown that is not back-stopped by financial sustenance of the kind that was given by the government of  Malaysia, will again fail to contain the disease. But  the harm that it will do to the economy will persist for  years to come. This is because once an airline, a hotel chain, a bank, a mobile telephony company,  an industrial enterprise,  a restaurant or a cinema hall goes bankrupt, debt recovery procedures kick in that make it impossible for it to restart again.  Thus the end of the pandemic will not therefore re-start these enterprises automatically.

Delhi example worth emulating

One way to drastically shorten the fight against the pandemic and minimise the damage to the economy at the same time would be to follow the example that Delhi has set, first during the lockdown, and then after it was lifted at the end of May. Kejriwal, Sisodia, and their ministers understood from the very first day  that the lockdown would deprive millions of workers of their livelihoods for no fault of theirs or their employers, so they  had a moral duty to minimise the hardship the poor, in particular,  would have to suffer.

The government, helped by cadres of the Aam Admi Party, did not  wholly eliminate the distress caused by the sudden loss of jobs because a large proportion of the wage earners, especially the migrant workers,  lived in distant  suburbs across the Uttar Pradesh and Haryana borders, and were therefore prevented  from entering the city by the stoppage of metro trains and buses. But  it did  reduce the stress  and anxiety in the resident working class of the National Capital Territory and therefore its willingness to abide by the lockdown in the containment areas.

The other key decision of the Delhi government – one that the lieutenant governor tried recently to countermand before taking a U-turn –  was to allow mildly affected patients to be treated at home. This reduced the pressure on the city’s medical infrastructure

The second is the introduction of rapid antigen testing on June 18. While this test has been criticised by many, including the WHO, on the grounds that it misses many people in the early stages of the infection, it allows for a much earlier start of treatment of those it has detected, because the results become available in half an hour instead of two days. This has led to a rapid increase in the number of recoveries, and consequently a plateauing of active cases after June 20. It has also raised  the recovery rate to 0.71 %, substantially  above the national average of  0.54%. As the table below shows, this speeded up the daily recoveries dramatically from an average of 400 a day till June 8 to 3,000 a day from June 17. This stopped the number of active cases from rising any further,  and may have begun a marginal decline from June 27.

As a result, the ratio  of recovered to total cases  has risen from 42.7% on May 31 to  66.5% on June 30, at an average of 0.71% per day. This is one reason why Delhi’s graph of new cases and new recoveries presents us with some room for optimism compared to the all India graph:

Since three-quarters of all COVID-19 cases are concentrated in the dozen or so largest cities of India (Delhi and Mumbai alone account for almost a third), if all of them follow Delhi’s example, the number of cases could peak, and the pandemic begin to draw down, earlier than otherwise.

But even here a caveat is needed: Delhi’s testing volumes need to be ramped up and now slowed down.

Note: This article has been edited to clarify that the figure for recoveries in column 2 is the cumulative total till that day, and the difference between total daily recoveries each day is the daily increase in the number of recoveries. It has also been edited to add graphs plotting daily new cases and daily recoveries for India and Delhi. The earlier version erroneously made a prediction of COVID cases “peaking” in September, based on the trajectories of recovered cases and active cases. In fact, cases will peak only when daily new recoveries equal daily new cases.